Winter and summer in Salt Lake City are long. The summers are dry and the winters are snowy and cold. Fall and spring in the city are brief. However, they offer very comfortable periods. The city also receives massive storms from the Pacific Ocean between the months of October and May.
The best time to visit the city is in autumn. This is normally when its drier and a little warmer compared to spring. The temperatures are very comfortable during the day. In mid-October, pacific storm impact the city, but these are infrequent. So, autumn is the best season, you will need to start planning a few months before your trip.